<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>id和类选择器</title>
	<style>
		.div1{
	width:800px;
	height:80px;
	background-color:red;

}

#id2{
    background-color: lightblue;
}

.div2{
    width:500px;
    height:40px;
    background-color:black;
}
#id4{
	background-color:green;
}

	</style>

</head>
<body>
	<div class="div1"></div>
	<div id="id2" class="div1"></div>
	<div class="div1"></div>
	<div class="div2" id="id4"></div>
	<div class="div2"></div>
	<div class="div2"></div>
</body>
</html>